First off, if you don't practice, and then take a few weeks off? then you should be properly amazed that you retained anything at all of your routine. And I really suspect that you have far from 'nailed' it - you MAY remember it in a general way, but you certainly are not dancing it yet...
You'll need to devote time and energy to this or you will find that you will never progress. You need to work on it a lot so that your body can retain the movement. At the rate you are going, I suspect that after 2 months of this all you can do is 'step through' the 'routine'. If you had practiced and not taken the time off, then after 2 months you should be applying technique to the 'memorized steps' to make it look like dancing.
Top competitors keep their routines and choreography FOR YEARS. They learn them over a period of time (days or weeks) and then spend the next year or so making it good. It takes less time as you do more dancing because the movement will eventually be made up of movemtns that you already 'know' (in other words, right now you are spending time and money learning basic movements, being corrected for posture and so on, that as a more advanced dancer will already be part of your 'package'). In the meantime, you get out of dancing exactly what you put into it, so put some time into practice (unless you expect your instructor to drag you through the comp) so that you hold up your part of the dance.
Actually, it is YOUR job to 'refresh and remember' stuff.